128 PHYSIOLOGY. 



But let us now turn from the air and respiration to 

 another, yet closely allied subject. 



The Need of the Removal of Waste. When we 

 awaken on a cold winter morning we are likely to find that 

 the fire in our hard coal stove has burned low. Not enough 

 heat is given out. What is the trouble ? Is it merely that 

 more coal is needed ? We put another hod of coal in the 

 magazine (though some usually remains). Does this bring 

 the desired result ? No. We open the draft. Is this suffi- 

 cient? It is not. We must shake down the grate and 

 clean out the clinkers. The removal of waste is often 

 more necessary than the addition of a fresh supply of ma- 

 terial. It is often a more serious matter to have the waste 

 pipe leading to the sewer clogged than to have the water 

 supply cut off. It is often more to be desired that the 

 garbage cart take away decaying matter than that the 

 bread wagon arrive. The demands of nature for the ex- 

 pulsion of excreta are imperative, while we can withstand 

 the cravings of hunger for a while. So we shall turn our 

 attention for the present to the immediate demand for the 

 removal of wastes, and later consider the equally impor- 

 tant, but less importunate, question of supply and renewal. 



READING. (i) Bacteria, (2) Dust and Its Dangers, 

 (3) Drinking Water and Ice Supplies, Prudden ; Ventila- 

 tion and Warming of School Buildings, Morrison; Sanitary 

 Conditions of ScJioolJionses, Lincoln (American Public 

 Health Association); Disinfection, Sternberg (American 

 Public Health Association) ; Micro-Organisms and Disease, 

 Klein ; The Wilderness Cure, Marc Cook. 



Summary. i. Lung diseases usually accompany close confine- 

 ment, but are rare with those living in the open air. 



